Ball bearing, screw jack, pumping mechanism



D. E. GlLLUM BALL BEARING, SCREW JACK, PUMPING MECHANISM Filed March 2,195a 2 Sheets-Sheet 1 Prime fl/orer [Speed amrnezl) E ml 'N N T W 00E rVa/ 7 0W. A

DONALD E:

Nov. 24, 1959 D. E. GILLUM 2,913,910

BALL BEARING, SCREW JACK, PUMPING MECHANISM Filed March 2. 1953 2Sheets-Sheet 2 J06 I J10 I 1 7 50! M; ji'rfl.

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United States Patent 2,913,910 BALL BEARING, scusw JACK,

. MECHANISM Application March 2, 1953, Serial No; 339,688

8 Claims. (Cl. 74-57) PUMPING This invention relates to a novel methodof operating pumping equipment, particularly of the deep wellreciprocating type and to improved methods and means for effectivelydriving a deep well pump.

In a deep well, reciprocating type pump of the character often used indeep well oil wells, a largeamount of energy must be supplied to thepumping system to raise the moving parts of the well (pump rod andpiston) together with the oil or other fluid; a relatively small amountof energy is required on the downstroke. The load on the driving motorvaries over a wide range and is influenced by a large number of factors,including gravity of oil being pumped, the presence and amount of gas inthe oil, the presence and amount of sand in the oil, the temperature andviscosity of the oil, the degree of wear in the working elements,whether the hole is straight or crooked, etc. It has been recognizedrepeatedly, in the past, that any prime mover and. actuating apparatuswhich is subject to great changes in load and energy output is incapableof operatingefliciently. For this reason, reciprocating deep well pumpshave been provided with weights which attempt to counterbalance theweight of the sucker rods and pump piston, but these expedients are notsatisfactory and extremely heavy, massive counterweights must be used inan attempt to counterbalance the reciprocating partsand the weight ofthe column of oil being lifted. These counterweights effectively doublethe total weight of the mass being moved and increase the inertiaeffect, requiring the use of more powerful prime movers; the inertiaforces are often sufficiently great to cause breakage of pump rods uponreversal of the pump at the end of a stroke. Attempts have also beenmade to employ pneumatic counterbalances (as in Patents 1,624,577,1,775,733 and 2,072,595) but these schemes have been found to beineffective.

Furthermore, the usual Walking beam arrangement used at a deep well pumpintroduces a bothersome problem in translating an oscillatory motion ofthe beam and arcuate movement of the beam end into a rectilinear motionof the sucker rod and pump rod. In an attempt to overcome thisdifiiculty, hydraulic lifting units have been tried (see Patents2,247,238, 2,292,331, 2,313,406 and 2,366,777 for example) but theircomplexity, cost, and relative fragility precluded their extensive use.Mechanical drives, such as the Scotch yoke of Patent No. 1,465,671 orthe more intricate internal gear rack and pinion arrangement of PatentNo. 2,200,292, have been found unsatisfactory because they aremechanically not efficient and subject to Wear, breakage, etc. in fieldoperation.

The present invention, in one of itsaspects, relates to a method ofoperating a vertically reciprocatable pump whereby, kinetic energy isutilized to best advantage. The preferred method of operation. storeskinetic energy in an accumulator and imparts such energy directly to thepump stem to initiate an upstroke. ever, employs a rotating energyaccumulator in which The method, how- Patented Nov. 24, 1959 energy isstored and released in timed relation to the pump strokeand the energyrequirements of the system, the prime mover contributing only whenenergy level in the accumulator drops below a predetermined minimum.Another aspect of the invention is concerned with effective means forreciprocating a sucker rod and pump stem without the use of walkingbeams or complicated hydraulic systems; with an arrangement wherebyrotary motion may be eflectivelytranslated into reciprocation of a pumpstem; with driving means including a constantly rotating prime mover, atransmission connecting the prime mover with a ball bearing screw jackin operative engagement with a pump stem and means, controlled byrectilinear movement of the pump stem, for engaging and disengaging thetransmission, this system (in connection with suitable energyaccumulators) permitting pumping operations to be carried out with aminimum of inequality in load upon the prime mover and with amaximumutilization of kinetic energy available in the reciprocating mass ofpump rods, etc.

One of the 'objects of the present invention, therefore, is to discloseand provide a novel method of operating a reciprocating pump having apump stem, whereby a prime mover is disengaged from the pump stem duringa part of the downstroke and energy is stored in an accumulator and thendirectly applied to the pump stem to initiate the upstroke thereof.

Another object of the invention is to describe a method of operationwhereby energy is stored within and released from a flywheel, suchflywheel being connected to and disconnected from a prime mover in apredetermined manner controlled by the pump stroke and the energy levelin the flywheel.

Another object is to disclose and provide simple and effective means forimparting rectilinear, reciprocating motion to a pump assembly by theuse of a ball bearing screw jack.

A further object is to disclose and provide a novel means forcontrolling pumping operations, absorbing energy in accumulators duringportions of a downstroke, and releasing and applying such energy to thepump stem and driving means in timed relation to the stroke of the pumpand energy output of the prime mover.

A related object of this invention is to provide a long stroke type ofpumping mechanism that is capable of effectively storing kinetic energydeveloped by the action of gravity upon the combined mass of thevertically reciprocating pump elements during the downstroke andutilizing the stored kinetic energy to augment the energy developed bythe prime mover during the upstroke.

Another object of my invention is to provide a long stroke type ofpumping mechanism that does not utilize counterbalances to compensatefor the weight of the reciprocating parts that operates with highmechanical efliciency.

A further object of my invention is to provide a long stroke type ofpumping mechanism that operates with high mechanical efliciency, therebysubstantially reducing frictional wear, andrequiring less upkeep andrepair, as well as less power to operate.

Otherobjects and advantages of my invention will become apparent fromthe following detailed description and accompanying illustrativedrawings in which:

lifting mechanism.

Fig. 3 is a schematic wiring diagram indicating the relative position ofthe various limit switches that control the engagement .anddisengagement of the forward and reverse driving clutches and showingthe relationship of these switches to the activating element of thelongitudinally moving member.

Fig. 4 is an alternative embodiment of .a pumping mechanism utilizingthe ball bearing screw jack combination.

Fig. 5 is a cross sectional view .taken on the lines VV of Fig. 4showing one manner in which the .rotation of the revolving screws issynchronized.

Fig. 6 is a cross sectional view taken on the line VI-V-I of Fig. 1showing one construction for preventing the longitudinally moving screwfrom rotating.

In the illustrative form of apparatus of Figs. 1, 2, and 3 the drivingmechanism is shown positioned above a well provided with the casing 10having a usual casing head 11 at its upper end. Within the casing andextending downwardly .into the well is a tubing or production string 12suitably suspended by a conventional tubing head support 13. Aproduction outlet is indicated at 14. Extending downwardly through thetubing is a string of sucker rods or pump rods 15 going down to a pumpof any suitable and customary construction located at the desired levelwithin the well. The upper end of the string of sucker rods mayterminate in a polish rod which is coupled to a pump screw shaft 16extending upwardly through the casing head 11.

In order to adequately protect the lower portion of the pump screw shaftfrom contamination with oil being pumped, the lower portion of suchshaft may be enclosed within a tubular housing 18, the bottom of suchhousing being provided with suitable glands 19 through which extends apolish rod attached to the upper end of the series of sucker rods. Theupper end of the housing or protective tubing 18 may be connected to thebottom of the housing 20.

Means are provided for imparting a rectilinear reciproeating motion tothe pump screw shaft. Such means may comprise a nut sleeve 17 whichsurrounds the pump screw shaft 16. Means are provided for rotating thenut sleeve while restraining it from longitudinal motion. Such means maycomprise a housing 20 mounted upon the casing head 11 covered by a plate21 forming a part of an auxiliary accumulator cage 22. The nut sleeve 17is mounted for rotation by means of antifriction bearings 23 and 24suitably held in recesses formed in the bottom of housing 20 and in baseplate .21 of the auxiliary accumulator cage 22. The bearings cooperatewith the nut sleeve so as to permit rotation of the nut sleeve whilerestraining such sleeve against longitudinal motion.

The pump screw shaft 16 and the nut sleeve 17 constitute a ball bearingscrew jack. The pump screw shaft is provided with a helical groove, theinterior of the nut sleeve being provided with a complementary groove,

force being transmitted from the nut sleeve to the screw shaft and viceversa by balls that interengage the complementary grooves of the twomembers. vBall bearing screw jacks are well-known and one form is shownin Patent No. 2,343,507. Single, double or triple grooves may be formedin the nut and screw, each'complementary set of grooves having its ownball circulating conduit formed in the nut sleeve. One of such ballcirculating conduits is indicated by .17.

The upper end of the pump screw shaft 16 extends through the auxiliaryaccumulator cage 22 and into a guide tube mounted above the accumulatorcage. In order to permit reciprocating motion of the pump screw shaftwhile restraining it .from rotation, a wall or walls of the guide tube30 may be provided with a longitudinally extending groove or grooves andthe upper end of the pump screw shaft 16 may carry a guide wheel 31 ,(orkey) in sliding or rolling engagement with such groove or grooves.

Means are provided for absorbing kinetic energy from the pump screwshaft or pump stem when such pump stem descends under the force ofgravity. Such means comprise a directly responsive accumulator which, inthe form illustrated in the drawings includes a series of springs 35,36, and the like, positioned in the accumulator cage 22. Resting uponsuch springs is a pressure plate 37 provided with an upstanding centralneck 38 extending into the lower portion of guide tube 30. The neck 38fits loosely around the pump screw 16. The upper end of such pump shaft16 is provided with a head 39 adapted to contact the top of the neck 38during the last portion of the downstroke.

Although various methods and arrangements may be utilized for drivingthe pump, the arrangement illustrated in the drawings has been foundvery effective. The lower end of the nut sleeve for example may beprovided with a bevel gear 40, the housing 20 including a side port inwhich there is journaled (in suitable bearings) a driving shaft 41provided with abevel gear 42 in operative engagement with bevel gear 40and an external flexible coupling 43 adapted to be connected to adriving means.

The power transmission system, shown in Figs. 1 and 2 by way of example,comprises a speed governed, prime mover 51 of any suitable type such asan electric motor 'or an internal combustion engine (gasoline, diesel orgas engine). Prime mover 51 is coupled to an energy storing means suchas a flywheel .52 through an overrunning clutch 53 secured to flywheel52 and coupled to the prime mover by shaft .54. This type of clutchpermits the flywheel to revolve faster than the prime mover at any timewhen the angular velocity of the flywheel exceeds the correspondingangular velocity of the prime mover. The details of construction of anoverrunning clutch do not constitute a part of this invention and arewell known to those skilled in the art.

Flywheel 52, preferably dynamically balanced, is mounted on a shaft 55that is journaled in suitable bearings supported by bearing pillowblocks 56 and 57.

A positive transmission means, for example a chain sprocket 58, issecured to shaft 55 and is preferably positioned between pillow blocks56 and 57. Shaft 55 is also referred to hereinas the first shaft.

A first, or forward driving, automatically operable clutch means 59 isattached, on one side, to a shaft 60 that is journaled in a bearingsupported by bearing pillow block 61. This shaft is parallel to shaft55. A chain sprocket 62 is secured to shaft 60 between clutch 59 andbearing pillow block 61 and is positioned in alignment with sprocket 58secured to shaft 55. A chain 63 connects sprocket 58 directly tosprocket 62. Shaft 60 is also referred to herein as a countershaft.

The other side of clutch 59 is attached to a shaft 63 journaled in abearing supported by bearing pillow block 64. Shaft 63 extends beyondpillow block 64 and a chain sprocket 65 is secured to that portion ofthe shaft that overhangs pillow block 64.

A shaft 66 is attached to the other side of flexible coupling 43 fromthat to which shaft 41 is attached, and is journaled in a bearingsupported by a bearing pillow block 67. This shaft is parallel to shafts55 and 60. Shaft 66 is provided with a chain sprocket 68 secured to itand positioned in alignment with sprocket 65. Preferably sprocket 68 issecured to shaft 66 between flexible coupling 43 and bearing pillowblock 67. A chain 69 directly connects sprocket 68 and sprocket 65.Shaft 66 extends beyond bearing pillow block 67 and the other end isattached to one side of a second, or reverse driving, automaticallyoperable clutch means 70. Shaft 66 in combination with shaft 41 is alsoreferred to in this application as the nut shaft.

The opposite side of reverse driving clutch 70 is connected to a shaft71 journaled in a bearing support by pillow block 72. A chain sprocket73 is secured to shaft 71 and is positioned to align with and engagechain 63 on the outer side of the chain whereas sprockets 58 and 62engage the chain on its inner side. This manner of 1' coupling sprocket73 to chain 63 permits the sprocket to rotate in the opposite directionfrom sprockets 62 and 58 when chain 63 is being driven. Thepreferredform of clutch is a magnetic type of clutch. The details ofconstruction of automatically operable clutches, such as magneticclutches, do not constitute a part of this invention and are well knownto those skilled in the art.

A suitable gear transmission (to increase or decrease the rotationalspeed, as indicated by the requirements of an installation) may beincluded in the system at 74 or positioned between flywheel 52 and'shaft 55.

The operation of the pumping system and apparatus shown in Figs. 1 and 2is as follows:

Power to revolve the nut sleeve element 17 and raise the pump screwshaft 16 is transmitted from prime mover complished by closing thenormally open limit switch 75 andenergizing the. forward driving clutchactuating coil 83. Whenever limit switch 75 is closedflthe circuit iscompleted from the power terminal 76 to power terminal 77 through line78, closed switch 75, holding coil .79, line 80, normally closed limitswitch 81, line 82, forwarddriving clutch actuating coil 83, junction93, and line 84. Holding coil 79 will keep limit switch 75 closed aslong as the circuit remains unbroken, thereby continuing to energizeactuating coil 83 that holds clutch engaged.

When pump screw shaft 16 reaches the end of the upstroke, as shownschematically in Fig. 3, an engaging member such as head 39 or a wheel31, contacts normally closed limit switch 81 separating the contactpoints and interrupting the circuit through holding coil 79 andactuating coil 83, causing them ,to become de-.energized. This allowslimit switch 75 to open and disengages clutch .59, disconnecting nutsleeve element 17 from prime mover 51 and flywheel 52, and stopping theupward movement of pump screw shaft 16. V

The load imposed on the prime mover during the upstroke will havedecreased its angular velocity below that at which it normally travelsunder its governed output speed. The disengagement of forward drivingclutch 59 relieves the prime. mover of the necessity ofdriving therotating member of the screw jack combination and allows the energyoutput of the prime mover to-overcome the inertia of the fllywheel andraise its angular velocity until such a time as the angular velocity ofthe flywheel exceeds the angular velocity of the prime mover.

Gravity acts on the unsupported mass normally causing pump screw shaft16 to move downwardlyat increasing speed, and kinetic energy isgenerated. The downwardly moving pump screw shaft imports acounterrotation to nut sleeve element 17. v

The downwardly moving engaging member on pump screw shaft 16 nextcontacts a normally open limit switch 85 provided with a holding coil88, and closes the points of the switch. This completes the circuitbetween power terminal 76 and power terminal 77 through line 78,junction 86, line 87, the closed contact points of normally open limitswitch 85, holding coil 88, line 89, normally closed limit switch 90,line 91, reverse driving clutch actuating coil 92, junction 93, and line84. Current flowing through holding coil 88 will continue to hold limitswitch 85 closed and continue to energize actuating coil 92. As long asactuating coil 92 is energizedgclutch 70 remains engaged.

The kinetic energy generated by gravity acting on the unsupported massis transmitted by the counterrevolving nut sleeveelement 17 to flywheel52 through the engaged reverse driving clutch 70, and sprocket 73reversely coupled to chain 63. The kinetic energy transmitted to theflywheel normally progressively increases during the downstroke rotatingthe fiywheel at an ever increasing arisen angular velocity. Overrunningclutch 5 3 automatically disconnects flywheel 52 from prime mover 51whenever the angular velocity of: the flywheel exceeds the angularvelocity of the prime mover, thus permitting the flywheel connects thereversely revolving nut shaft to the flywheel,

translating the reverse motion of the nutshaft and permitting the nutshaft to drive the flywheel in the same manner as it is normally drivenby the prime mover. If

coil 92 is energized before the angular velocity of the nut shaft isequal to the corresponding angular velocity at which flywheel 52 isnormally driven by the prime mover, a load will'be placed on theflywheel causing the prime mover to supply power to the nut shaft duringa portion of the downstroke. If coil 92 becomes energized when theangular velocity of the nut shaft is greater than that of flywheel 52,then the nut shaft will drive the, flywheel. In either instance clutch70 will be subjected to strain at the time of engagement that becomesmore severe as the, difference between the angular velocities of ,the.nut shaft and flywheel increases. The preferred procedure is toposition limit switch 85, with ,respect to the engaging member on pumpscrew shaft 16,

so that it will be closed and energize actuating coil 92, engagingclutch 70, when the angular velocity of the flywheel corresponds to theangular velocity of the counterrevolving nut shaft; at this instantclutch.70 can be engaged without subjecting it to undue strains. If ahighly viscous material is to be pumped, considerable resistance on pumpscrew shaft 16 contacts normally closed limit switch 90, separating thecontact points. This interrupts the circuit and the reverse, ordownstroke clutch actuating coil 92 and holding coil 88 are de-energizedcausing clutch 70 to become disengaged and opening limit switch Theengaging member on pump screw shaft 16 continues to move downwardly andin passing contacts normally open limit switch 75 opening it stillfurther asit moves past it.

, Head 39 secured to the end of pump screw shaft 16 next engages the endof neck 38 ofpressure plate 37 and the momentum of the downwardly movingmass for'ces neck 38 and pressure plate 37 downwardly, compressingsprings 35 and 36, and arresting the downward progress of descendingpump screw shaft 16. The energy thus stored in springs 35 and 36 isreleased against the pressure plate 37 as soon as the downward movementof the pump screw shaft ceases, forcing neck 38 yviolently upward andcausing head 39 at the end of pump screw shaft 16 to move upwardly. Thiscauses the engaging member to again contact normally open limit switch75, closing the points and again completing the circuit through theforward or upstroke clutch actuating coil 831and holding coil 79. Thistie-engages clutch 59, again connecting nut sleeve element 17 toflywheel 52. Since flywheel 52 is traveling at a considerably greaterangularvelocity than that at which it is normally driven by prime mover51, the kinetic energy stored in the flywheel will serve to drive thenut shaft causing nut sleeve element 17 to revolve and raise pump screwshaft 16.

From the above description it is seen that during a portion of thedownstroke and a portion of the upstroke,

prime mover 51 may be temporarily disconnected from the more rapidlyrevolving flywheel by means of the overrunning clutch 53 and is undernoload. As the pump screw shaft continues to rise, the energy stored inthe flywheel 52 is applied to raising the pump screw shaft therebyprogressively reducing the angular velocity of the flywheel until itagain coincides with the corresponding angular velocity of the primemover. At this point overrunning clutch 53 automatically connects theprime mover to the flywheel and the prime mover will now supplyadditional power to raise the pump screw shaft for the remainder of theupstroke, thereby starting a new cycle.

Fig. 4 represents a modification of the pumping mechanism shown inFig. 1. In this embodiment two ball bearing screw jacks are employed.The two pump screw shafts 101 and 102 are the rotating members and arerestrained from longitudinal movement While the two nut sleeve elements103 and 104 move longitudinally. Since nut sleeve elements 103 and 104are coupled together by yoke 105, no rotation can occur in either nutscrew element.

The screw members are rotatably mounted at each end on frictionlessbearings supported in bearing retainers 106, 107, 108 and 109. Bearingretainers 106 and 107 are secured to an upper platform 110 and bearingretainers 108 and 109 are secured to an intermediate platform 111. Bothplatforms 110 and 111 form a part of supporting frame work 112.

The lower portion of one of the pump screw shafts, for example shaft 102is provided with a suitable transmission means such as a bevel gear 113secured to pump screw shaft 102. A corresponding bevel gear 114 issecured to a shaft 115 journaled in bearings retained in a bearingretainer 116 securely attached to supporting frame work 112 andpositioned to permit gear 114 to properly engage gear 113. The other endof shaft 115 is secured to one side of flexible coupling 43. Shaft 115corresponds to shaft 41 of the embodiment in Fig. l.

A transmission means such as a chain sprocket 117 is secured to screwmember 102. A second and corresponding sprocket 118 is secured to screwmember 102 and positioned to be in alignment with sprocket 117. A chain119 engages sprockets 117 and 118 and synchronizes the rotation of thetwo pump screw shafts.

A third platform 120 is located above the transmission mechanism andprovided with suitable spring retainers that support springs 121 and122. The spring retainers are provided with an axial bore large enoughto permit free passage of the pump screw shafts. The upper end ofsprings 121 and 122 are provided with a pair of pressure plates 123 and124 having an axial bore extending therethrough, large enough to permitfree passage of pump screw shafts 101 and 102. Springs 121 and 122 servea similar function as springs 35 and 36 in the directly responsiveauxiliary energy accumulator and braking mechanism shown in Fig. 1, theonly difference being that the lower end of the nut sleeve elementsengages the a compression member instead of head 39 as in Fig. 1.

T he end of a polish rod 126 at the upper end of a sucker rod string(not shown) is secured to yoke 105 and positioned to align the polishrod 126 over tubing 12. Platforms 111 and 120 are provided withclearance holes to permit free passage of polish rod 126. Base 128 offramework 112 is secured to tubing 12. The sides of framework 112 may becovered with sheathing if desired to exclude dirt and sand from thescrew jack and transmission mechanisms. mover assembly required tooperate the device shown in Fig. 4 can be the same as that shown'in Fig.2 with shaft 115 connected to the flexible coupling instead of shaft 41.

From the foregoing description it will be apparent that I have provideda novel pumping mechanism capable of utilizing a substantial part of thekinetic energy developed during the downstroke, by storing the energy ina flywheel and using the stored energy to raise the reciprocatingelement or the screw jack during the upstroke, thereby The transmissionmeans and prime 8 relieving the prime mover of an appreciable portion ofthe load to which it would be otherwise subjected. My assembly permitsthe prime mover to operate at substantially no load during the majorityof the downstroke and for a portion of the upstroke thereby conservingenergy.

An inherent feature of the ball bearing screw jack mechanism is that thepump screw shaft is not limited in length by factors such as are presentwhere a walking beam type of mechanism is used, and pump strokes of anydesired length are possible.

Another characteristic of the ball bearing screw jack lies in the factthat its operation is substantially frictionless. This factor permitsthe revolving element to efficiently drive the longitudinally movingmember, such as during the upstroke, and permits the downwardly movingmember, on the reverse stroke, to effectively drive the revolvingmember.

My novel pumpingsystem reduces the peak load requirements normallyencountered in existing systems, thereby permitting the use of a primemover of smaller capacity.

My novel pumping mechanism does not require counterbalances, thereforethe inertia of the mass in motion is reduced to a minimum.

It is contemplated that modifications of the elements used in thepumping mechanism may be also employed, for example the ball bearingscrew jack may have a single, double, or triple groove construction andthe co-acting members may be interengaged by balls that are of uniformdiameter, or the balls may vary in size and be arranged in the groovesin proper sequence. Likewise any other satisfactory driving ortransmission means, capable of performing the functions described, maybe substituted.

It is understood that other directly responsive energy accumulator meansmay be used in place of the exemplary spring and pressure platearrangement shown, and such other accumulator means may includecompressible fluids such as air or gas in which energy may be stored andthen released.

Having described in an exemplary manner my invention, it is to beunderstood that it is not intended to limit the scope of the inventionto the exact details set forth herein which may be varied wihoutdeparting from the spirit of the invention as set forth in the appendedclaims.

I claim: 1. In a long stroke pumping mechanism, the combination of: aprime mover; a flywheel coupled to said prime mover through anoverrunning clutch; a ball bearing screw jack comprising a rotatable nutmember and a longitudinally movable screw member; a forward drivingclutch means and transmission means connecting said nut member to saidprime mover when said forward driving clutch is engaged; a reversedriving clutch means and transmission means reversely engaging said nutmember with said flywheel when said reverse driving clutch means isengaged; and means controlled by longitudinal movement of said screwmember for engaging and disengaging said forward and reverse drivingclutch means.

2. A long stroke pumping mechanism according to claim 1 wherein theforward and reverse driving clutch means are magnetic clutches.

- 3. In a long stroke pumping mechanism, the combination of: a primemover; a flywheel coupled to said prime mover through an overrunningclutch; a ball bearing screw jack comprising a rotatable nut member anda longitudinally movable screw member; a forward driving clutch meansand transmission means connecting said nut member to said prime moverwhen said forward driving clutch is engaged; a reverse driving clutchmeans and transmission means reversely engaging said nut member withsaid flywheel when said reverse driving clutch means is engaged; meanscontrolled by longitudinal movement of said screw member for engagingand disengaging said forward and reverse driving clutch means;

and a braking and resilient energy storing means engageable by saidscrew member whereby downward movement of the screw member is arrestedand energy is stored in said resilient energy storing means, said energystoring means returning said stored energy to said screw member aftersaid screw member has come to rest, to initiate upward movement of saidscrew member.

4. A long stroke pumping mechanism according to claim 3 wherein thebraking and resilient energy storing means comprises a plurality ofcompression springs fixedly supported at their lower end and havingtheir upper end in contact with a movable compression member, saidcompression member being engageable by means of said screw member.

5. A long stroke pumping mechanism comprising: a prime mover; a flywheelcoupled to said prime mover through an overrunning clutch, said flywheelbeing mounted on a first shaft; a countershaft provided with a firstclutch means; a nut shaft provided with a second clutch means;transmission means connecting said first shaft and countershaft fordirect connection; transmission means connecting the countershaft withthe nut shaft through said first clutch means; transmission meansconnecting the nut shaft reversely through said second clutch means tosaid direct connection transmission means connecting said first shaftand countershaft; a ball bearing screw jack comprising a verticallymovable screw mem ber and a rotatable nut member; transmission meansconmeeting said nut member to said nut shaft; means controll-ed bylongitudinal movement of said screw member for engaging and disengagingsaid first and second clutch means; a braking and resilient energystoring means engageable by said screw member, whereby the downwardmovement of the screw member is arrested and energy is stored in saidresilient energy storing means, said resilient energy storing meansreturning said stored energy to said screw member, after said screwmember has come to rest, to initiate upward movement of said screwmemher.

6. Means for imparting to and storing energy from a verticallyreciprocating means comprising, in combination: a prime mover and aflywheel; antifriction screw means including a vertically reciprocatingnonrotatable screw member and a driving nut means associated therewith,said screw member and said nut having cooperable complementary spiralgrooves, ball bearings antifrictionally connecting said screw member andsaid nut means and movable in said grooves, and means for circulatingsaid ball bearings; means for holding said nut means againstlongitudinal movement; drive means for rotating said nut means andincluding a first clutch means connecting said nut means with said primemover whereby rotation imparted to said nut means raises said screwmember; a second clutch means associated with said nut means and saidflywheel, said second clutch means being adapted to transfer energy fromrotation of said nut means upon descent of said screw member to saidflywheel above a predetermined speed of rotation; means positioned alongthe path of descent of said screw member for'disconnecting said secondclutch means from said flywheel; directly responsive accumulator energymeans for cushioning and stopping descent of said screw member and forstoring energy imparted thereto by said falling screw member toimmediately initially impart upward movement to said screw member; meansfor imparting energy stored in said flywheel to said screw member at ,aselected point along 10 its ascending path and until transfer of saidstored energy is decreased to a preselected value; and means for thenoperatively connecting said prime mover through said first clutch meansto said driving nut means for imparting energy to said screw member tocontinue ascent thereof at a preselected rate.

7. Means for imparting to and storing energy from a verticallyreciprocating means comprising, in combination: a prime mover and aflywheel; antifriction screw means including a vertically reciprocatingnonrotatable screw member and a rotatable nut means cooperablyassociated therewith; means to hold said rotatable nut means againstlongitudinal movement; first means releasably coupling said nut means tosaid prime mover to rotate said nut means to raise said screw member toa selected height; second means releasably coupling said nut means tosaid flywheel; said second releasably coupled means being operative toconnect said nut means and said flywheel to impart energy from rotationof said nut means upon descent of said screw member to said flywheelabove a predetermined speed of rotation; means to stop descent of saidscrew member and to initially impart upward movement to said screwmember; said second releasably coupled means being operative to transferenergy stored in said flywheel to said rotatable nut means and to saidscrew member at a selected point along its ascending path until energythereby imparted to said screw member reaches a predetermined value;said first means releasably coupled to said nut means being thenoperative to connect said prime mover to said nut means for impartingenergy thereto to continue ascent of said screw member at a preselectedrate.

8. In a long stroke pumping mechanism, the combination of: a primemover; energy storing means; an overrunning clutch coupled to said primemover; a ball hearing screw jack means including a rotatable member anda longitudinally movable member; a first clutch means and associatedtransmission means connecting said rotatable member to the prime moverwhen said first clutch means is engaged; a second clutch means andassociated transmission engaging said rotatable member with the energystoring means when said second clutch means is engaged; and meansselectively connectable by longitudinal movement of the longitudinallymovable member for engaging and disengaging said first and second clutchmeans.

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